Method to make dual material finFET on same substrate

ABSTRACT

A method of fabricating a semiconductor device including proving a substrate having a germanium containing layer that is present on a dielectric layer, and etching the germanium containing layer of the substrate to provide a first region including a germanium containing fin structure and a second region including a mandrel structure. A first gate structure may be formed on the germanium containing fin structures. A III-V fin structure may then be formed on the sidewalls of the mandrel structure. The mandrel structure may be removed. A second gate structure may be formed on the III-V fin structure.

BACKGROUND

The present disclosure relates generally to semiconductor devices. Moreparticularly, the present disclosure relates to semiconductor deviceshaving a fin structure.

In order to be able to make integrated circuits (ICs), such as memory,logic, and other devices, of higher integration density than currentlyfeasible, one has to find ways to further downscale the dimensions offield effect transistors (FETs), such as metal-oxide-semiconductor fieldeffect transistors (MOSFETs) and complementary metal oxidesemiconductors (CMOS). Scaling achieves compactness and improvesoperating performance in devices by shrinking the overall dimensions andoperating voltages of the device while maintaining the device'selectrical properties. In view of the possibility of scaling reachingits limits, other semiconductor geometries, such as fin field effecttransistors (finFETs) have been considered.

SUMMARY

A method of fabricating a semiconductor device is provided that includesproviding a substrate having a germanium containing layer that ispresent on a dielectric layer, and etching the substrate to provide afirst region including a germanium containing fin structure and a secondregion including a mandrel structure. A first gate structure may beformed on the germanium containing fin structure. A III-V fin structuresmay then be formed on the sidewall of the mandrel structure. The mandrelstructure may be removed. A second gate structure may be formed on theIII-V fin structure.

In another aspect, a semiconductor device is provided. In oneembodiment, the semiconductor device includes a substrate having a firstdevice region and a second device region. The first device region mayinclude a p-type fin field effect transistor including a first finstructure comprised of a germanium containing material. The seconddevice region may include an n-type fin field effect transistorincluding second fin structure comprised of a III-V semiconductormaterial.

DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the present disclosure solely thereto, will best beappreciated in conjunction with the accompanying drawings, wherein likereference numerals denote like elements and parts, in which:

FIG. 1 is a side cross-sectional view of a semiconductor substratehaving a germanium containing layer that is present on a dielectriclayer, as used in accordance with one embodiment of the presentdisclosure.

FIG. 2 is a side cross-sectional view depicting one embodiment ofetching the semiconductor substrate to provide a first region includinga germanium containing fin structure and a second region including amandrel structure, in accordance with one embodiment of the presentdisclosure.

FIG. 3 is a side cross-sectional view depicting one embodiment offorming a first gate structure on the germanium containing finstructure, in accordance with the present disclosure.

FIG. 4 is a side cross-sectional view depicting forming a III-V finstructure on a sidewall of the mandrel structure, in accordance with oneembodiment of the present disclosure.

FIG. 5 is a side cross-sectional view depicting one embodiment ofremoving the mandrel structure.

FIG. 6A is a side cross-sectional view depicting forming a second gatestructure on the III-V fin structure, in accordance with the presentdisclosure.

FIG. 6B is a top down planar view of the structure depicted in FIG. 6A.

DETAILED DESCRIPTION

Detailed embodiments of the methods and structures of the presentdisclosure are described herein; however, it is to be understood thatthe disclosed embodiments are merely illustrative of the disclosedmethods and structures that may be embodied in various forms. Inaddition, each of the examples given in connection with the variousembodiments of the disclosure are intended to be illustrative, and notrestrictive. Further, the figures are not necessarily to scale, somefeatures may be exaggerated to show details of particular components.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a representativebasis for teaching one skilled in the art to variously employ themethods and structures of the present disclosure. For the purposes ofthe description hereinafter, the terms “upper”, “lower”, “top”,“bottom”, and derivatives thereof shall relate to the disclosedstructures, as they are oriented in the drawing figures.

The methods and structures disclosed herein provide fin structures, suchas fin field effect transistors (finFETs). As used herein, the term “finstructure” refers to a semiconductor material, which is employed as thebody of a semiconductor device, in which the gate structure ispositioned around the fin structure such that charge flows down thechannel on the two sidewalls of the fin structure and optionally alongthe top surface of the fin structure. In some embodiments, the methodsand structures disclosed herein provide a first conductivity finFEThaving a fin structure composed of a germanium containing material and asecond conductivity finFET having a fin structure composed of a III-Vsemiconductor material on the same substrate. By “same substrate” it ismeant that the first conductivity finFET, e.g., p-type finFET, and thesecond conductivity finFET, e.g., n-type finFET, are presentsimultaneously on the same substrate in different regions of the samesubstrate. Typically, the first conductivity finFET and the secondconductivity finFET are present on a same surface, e.g., upper surface,of the semiconductor substrate.

FIGS. 1-6 depict one embodiment of a method of fabricating a firstconductivity finFET 100 a, e.g., p-type finFET, having a first finstructure 10 composed of a germanium containing material and a secondconductivity finFET, e.g., n-type finFET 100 b, having a second finstructure 20 composed of a III-V semiconductor material on the samesubstrate 5.

FIG. 1 depicts one embodiment of a semiconductor substrate 1 having agermanium containing layer 4 that is present on a dielectric layer 3,e.g., buried dielectric layer 3. In some embodiments, the semiconductorsubstrate 1 includes a germanium containing layer 4 that is present on aburied dielectric layer 3, wherein the buried dielectric layer 3 ispresent on a base semiconductor layer 2. The semiconductor substrate 1may be a silicon germanium on insulator (SGOI) substrate or a germaniumon insulator (GOI) substrate.

The germanium containing layer 4 may be composed of silicon germanium(SiGe). In some embodiments, the germanium containing layer 4 may becomposed of silicon germanium (SiGe) or germanium (Ge). For example, thegermanium containing layer 4 may be composed of up to 99 wt. %germanium. In one embodiment, the germanium containing layer 4 comprisesfrom 1 wt. % germanium to 99 wt. % germanium. In another embodiment, thegermanium containing layer 4 is composed of 10 wt. % to 50 wt. %germanium. In yet another embodiment, the germanium containing layer 4is composed of 100 wt. % germanium.

The germanium containing layer 4 may be a single layer having acontinuous distribution of germanium, or it may be a graded layer havinga varying content of germanium included within different regions of thelayer. The thickness of the germanium containing layer 4 may range from5 nm to 5000 nm. In another embodiment, the germanium containing layer 4may have a thickness that ranges from 20 nm to 200 nm.

The germanium containing layer 4 is typically present on, e.g., indirect contact with, a dielectric layer 3 (also referred to as a burieddielectric layer). The term “direct contact” means that a first element,such as a first structure, and a second element, such as a secondstructure, are connected without any intermediary conducting, insulatingor semiconductor layers at the interface of the two elements. Thedielectric layer 3 may be composed of an oxide, nitride or oxynitridematerial. For example, when the dielectric layer 3 is composed of anoxide, the dielectric layer 3 may be silicon oxide. In another example,when the dielectric layer is composed of a nitride, the dielectric layer3 may be silicon nitride. The base semiconductor layer 2 may be asemiconducting material including, but not limited to Si, strained Si,SiC, SiGe, SiGeC, Si alloys, Ge, Ge alloys, GaAs, InAs, InP as well asother III/V and II/VI compound semiconductors.

In one embodiment, the semiconductor substrate 1 that is depicted inFIG. 1 may be formed by depositing the buried dielectric layer 3 on thebase semiconductor layer 2 and then depositing the germanium containinglayer 4 on the buried dielectric layer 3. The semiconductor substrate 1depicted in FIG. 1 may also be formed by wafer bonding methods. In yetanother embodiment, a germanium layer may be formed on the silicon oninsulator (SOI) layer of a silicon on insulator (SOI) substrate.Thereafter, the germanium layer and the SOI layer of the SOI substratemay be annealed to thermally mix the germanium from the germaniumcontaining layer with the silicon of the SOI layer to form the germaniumcontaining layer 4 of the semiconductor substrate 1 that is depicted inFIG. 1.

FIG. 2 is depicts one embodiment of etching the semiconductor substrate1 to provide a first region including germanium containing finstructures 10 and a second region including a mandrel structure 20. Morespecifically, the germanium containing fin structures 10 and the mandrelstructure 20 are typically formed from the germanium containing layer 4of the semiconductor substrate 1. The term “mandrel” denotes asacrificial structure that provides the deposition surface of a laterformed fin structure for the second region of the substrate 5. Themandrel structure 20 typically has a width W2 that is larger than thewidth W1 of the germanium containing fin structures 10. For example, inone embodiment, the width W2 of the mandrel structure 20 may range from15 nm to 45 nm, and the width W1 of each of the germanium containing finstructures 10 may range from 2 nm to 12 nm. In another embodiment, thewidth W2 of the mandrel structure 20 may range from 20 nm to 40 nm, andthe width W1 of the germanium containing fin structures 10 may rangefrom 5 nm to 10 nm.

In some embodiments, prior to etching the germanium containing layer 4,a dielectric cap layer 30 may be formed atop the germanium containinglayer 4. The dielectric cap layer 30 may be composed of an oxide,nitride or oxynitride layer. For example, the dielectric cap layer 30may be composed of silicon oxide or silicon nitride. The dielectric caplayer 30 may have a thickness ranging from 5 nm to 200 nm. In anotherembodiment, the dielectric cap layer 30 may have a thickness rangingfrom 10 nm to 100 nm. The dielectric cap layer 30 may be formed by adeposition or a forming method that is selected from the groupconsisting of chemical vapor deposition (CVD), chemical solutiondeposition, thermal growth, spin on deposition or a combination thereof.

Following the formation of the dielectric cap layer 30, the dielectriccap layer 30 and the germanium containing layer 4 of the semiconductorsubstrate 1 may be etched. In one embodiment, etching the dielectric caplayer 30 and the germanium containing layer 4 may include forming apatterned photoresist layer, i.e., photomask, on the dielectric caplayer 30, and over the germanium containing layer 4, and etching thedielectric cap layer 30 and the germanium containing layer 4 selectivelyto the photomask and the buried dielectric layer 3. In one embodiment, apattern is produced by applying a photoresist to the surface to beetched, exposing the photoresist to a pattern of radiation, and thendeveloping the pattern into the photoresist utilizing a resistdeveloper. Once the patterning of the photoresist is completed, thesections of the dielectric cap layer 30 and the germanium containinglayer 4 covered by the photoresist are protected to provide thegermanium containing fin structures 10 and the mandrel structure 20,while the exposed regions are removed using a selective etching process.As used herein, the term “selective” in reference to a material removalprocess denotes that the rate of material removal for a first materialis greater than the rate of removal for at least another material of thestructure to which the material removal process is being applied. Forexample, in one embodiment, a selective etch may include an etchchemistry that removes a first material selectively to a second materialby a ratio of 10:1 or greater. In one embodiment, the etch chemistry isselected to remove at least one of the germanium containing layer 4 andthe dielectric cap layer 30 selectively to the buried dielectric layer3. The remaining portion of the semiconductor substrate 1 may now bereferred to as a substrate 5, which has a dielectric upper surfaceprovided by the buried dielectric layer 3.

In one embodiment, the etch process for forming the germanium containingfin structures 10 and the mandrel structure 20 is an anisotropic etch.An anisotropic etch process is a material removal process in which theetch rate in the direction normal to the surface to be etched is greaterthan in the direction parallel to the surface to be etched. Theanisotropic etch may include reactive-ion etching (RIE). Other examplesof anisotropic etching that can be used at this point of the presentdisclosure include ion beam etching, plasma etching or laser ablation.

Each of the germanium containing fin structures 10 may have a heightranging from 5 nm to 200 nm. In one embodiment, each of the germaniumcontaining fin structures 10 may have height ranging from 10 nm to 100nm. In another embodiment, each of the germanium containing finstructures 10 may have a height ranging from 15 nm to 50 nm. Each of thegermanium containing fin structures 10 may have a width W₁ ranging from5 nm to 50 nm. In another embodiment, each of the germanium containingfin structures 10 may have width W₁ ranging from 8 nm to 20 nm. Adjacentgermanium containing fin structures 10 may be separated by a pitch P1ranging from 20 nm to 100 nm. In one embodiment, adjacent germaniumcontaining fin structures 10 may be separated by a pitch P1 ranging from30 nm to 50 nm.

FIG. 3 depicts one embodiment of forming a first gate structure 15 onthe germanium containing fin structures 10. In one embodiment, the firstgate structure 15 includes a first gate dielectric layer 13 and a firstgate conductor layer 14. The first gate dielectric layer 13 is typicallyformed on the channel portion of the germanium containing fin structure10.

The at least one first gate dielectric layer 13 of the first gatestructure 15 may be composed of any dielectric material includingoxides, nitrides and oxynitrides. In one embodiment, the at least onefirst gate dielectric layer 13 may be provided by a high-k dielectricmaterial. The term “high-k” as used to describe the material of the atleast one first gate dielectric layer 13 denotes a dielectric materialhaving a dielectric constant greater than silicon oxide (SiO₂) at roomtemperature (20° C. to 25° C.) and atmospheric pressure (1 atm). Forexample, a high-k dielectric material may have a dielectric constantgreater than 4.0. In another example, the high-k gate dielectricmaterial has a dielectric constant greater than 7.0. In one embodiment,the at least one first gate dielectric layer 13 is composed of a high-koxide, such as, for example, HfO₂, ZrO₂, Al₂O₃, TiO₂, La₂O₃, SrTiO₃,LaAlO₃, Y₂O₃ and mixtures thereof. Other examples of high-k dielectricmaterials for the at least one first gate dielectric layer 13 includehafnium silicate, hafnium silicon oxynitride or combinations thereof. Inone embodiment, the at least one first gate dielectric 13 may bedeposited by chemical vapor deposition (CVD). Variations of CVDprocesses suitable for depositing the at least one first gate dielectriclayer 13 include, but are not limited to, APCVD, LPCVD, PECVD, MOCVD,ALD, and combinations thereof. In one embodiment, the thickness of theat least one first gate dielectric layer 13 is greater than 0.8 nm. Moretypically, the at least one first gate dielectric layer 13 has athickness ranging from about 1.0 nm to about 6.0 nm.

The at least one first gate conductor layer 14 is formed on the at leastone first gate dielectric layer 13. The at least one first gateconductor layer 14 may be formed by a deposition process, such as CVD,plasma-assisted CVD, plating, and/or sputtering, followed byplanarization. In one embodiment, the at least one first gate conductorlayer 14 is composed of metal or a doped semiconductor. Examples ofmetals that may be employed for the at least one first gate conductorlayer 14 may include, but is not limited to, W, Ni, Ti, Mo, Ta, Cu, Pt,Ag, Au, Ru, Ir, Rh, and Re, Al, TiN, WN, TaN, TiAlN, TaAlN, and alloysthereof. One example of a doped semiconductor that is suitable for theat least one first gate conductor layer 14 is doped polysilicon.

In some embodiments, in which the first conductivity finFET that isformed in the first device region of the substrate 5 is a p-type finFET,the at least one first gate conductor layer 14 may include a metal thatis a p-type work function metal layer. As used herein, a “p-type workfunction metal layer” is a metal layer that effectuates a p-typethreshold voltage shift. In one embodiment, the work function of thep-type work function metal layer ranges from 4.9 eV to 5.2 eV. As usedherein, “threshold voltage” is the lowest attainable gate voltage thatwill turn on a semiconductor device, e.g., transistor, by making thechannel of the device conductive. The term “p-type threshold voltageshift” as used herein means a shift in the Fermi energy of a p-typesemiconductor device towards a valence band of silicon in the siliconcontaining substrate of the p-type semiconductor device. A “valenceband” is the highest range of electron energies where electrons arenormally present at absolute zero.

In one embodiment, the p-type work function metal layer may be composedof titanium and their nitrided/carbide. In one embodiment, the p-typework function metal layer is composed of titanium nitride (TiN). Thep-type work function metal layer may also be composed of TiAlN, Ru, Pt,Mo, Co and alloys and combinations thereof. In one embodiment, thep-type work function metal layer comprising titanium nitride (TiN) maybe deposited by a physical vapor deposition (PVD) method, such assputtering. Examples of sputtering apparatus that may be suitable fordepositing the p-type work function metal layer include DC diode typesystems, radio frequency (RF) sputtering, magnetron sputtering, andionized metal plasma (IMP) sputtering. In addition to physical vapordeposition (PVD) techniques, the p-type work function metal layer mayalso be formed using chemical vapor deposition (CVD) and atomic layerdeposition (ALD).

The at least one first gate structure 15 may be formed using deposition,photolithography and etch processes. The at least one first gatestructure 15 is formed on a channel portion of the at least onegermanium containing fin structure 10. For example, the material layersfor the at least one first gate dielectric layer 13 and the at least onegate conductor layer 14 may be deposited onto the silicon germanium finstructures 10 to provide a gate stack. Thereafter, the gate stack may bepatterned and etched to provide the at least one first gate structure15.

Specifically, and in one example, a pattern is produced by applying aphotoresist to the surface to be etched, exposing the photoresist to apattern of radiation, and then developing the pattern into thephotoresist utilizing a resist developer. Once the patterning of thephotoresist is completed, the sections of the stack of the at least onegate dielectric layer 13 and the at least one gate conductor layer 14covered by the photoresist are protected to provide the at least onefirst gate structures 15, while the exposed regions are removed using aselective etching process that removes the unprotected regions. Forexample, the portion of the at least one first gate dielectric layer 13and the at least one first gate conductor layer 14 that is present overthe second region of the substrate 5 including the mandrel structure 20may be removed. Following formation of the at least one first gatestructure 15, the photoresist may be removed.

FIG. 4 depicts one embodiment of forming III-V fin structures 40 on thesidewalls of the mandrel structure 20. The term “III-V semiconductor”denotes a semiconductor material that includes at least one element fromGroup III of the Periodic Table of Elements and at least one elementfrom Group V of the Periodic Table of Elements. Typically, the III-Vcompound semiconductors are binary, ternary or quaternary alloysincluding III/V elements. Examples of III-V compound semiconductors thatcan be used in the present invention include, but are not limited toalloys of gallium arsenic (GaAs), aluminum arsenic (AlAs), indiumgallium arsenic (InGaAs), indium aluminum arsenic (InAlAs), indiumaluminum arsenic antimony (InAlAsSb), indium aluminum arsenic phosphorus(InAlAsP), indium gallium arsenic phosphorus (InGaAsP) and combinationsthereof.

In some embodiments, the III-V fin structures 40 may be formed on themandrel structure 20 using an epitaxial deposition process. The terms“epitaxial growth and/or deposition” and “epitaxially formed and/orgrown” mean the growth of a semiconductor material on a depositionsurface of a semiconductor material, in which the semiconductor materialbeing grown has the same crystalline characteristics as thesemiconductor material of the deposition surface. In an epitaxialdeposition process, the chemical reactants provided by the source gassesare controlled and the system parameters are set so that the depositingatoms arrive at the deposition surface of the semiconductor substratewith sufficient energy to move around on the surface and orientthemselves to the crystal arrangement of the atoms of the depositionsurface. Therefore, an epitaxial semiconductor material has the samecrystalline characteristics as the deposition surface on which it isformed. For example, an epitaxial semiconductor material deposited on a{100} crystal surface will take on a {100} orientation. In someembodiments, epitaxial growth and/or deposition processes are selectiveto forming on semiconductor surface, and do not deposit material ondielectric surfaces, such as silicon oxide or silicon nitride surfaces.Therefore, in some embodiments, because the epitaxially grown III-V finstructures 40 are not formed on dielectric structures, such as thedielectric cap layer 30, or the dielectric layer that is present on theat least one first gate structure 15, the epitaxially grown III-V finstructures 40 are selectively deposited on the sidewalls of the mandrelstructure 20. The sidewalls of the mandrel structure 20 are composed ofa semiconductor material, such as germanium or silicon germanium.

Examples of various epitaxial growth process apparatuses that aresuitable for use with the present disclosure include, e.g., rapidthermal chemical vapor deposition (RTCVD), low-energy plasma deposition(LEPD), ultra-high vacuum chemical vapor deposition (UHVCVD),atmospheric pressure chemical vapor deposition (APCVD) and molecularbeam epitaxy (MBE). The temperature for epitaxial deposition process forforming the III-V fin structures 40 typically range from 550° C. to 900°C. Although higher temperature typically results in faster deposition,the faster deposition may result in crystal defects and film cracking.

In one embodiment, each of the III-V fin structures 40 may have a widthW3 ranging from 2 nm to 30 nm. In another embodiment, each of the III-Vfin structures 40 may have a width W3 ranging from 5 nm to 15 nm.

FIG. 5 depicts one embodiment of removing the mandrel structure 20. Inone embodiment, the mandrel structure 20 is removed by an etch that isselective to the III-V fin structures 40. The etch for removing themandrel structure 20 may also be selective to the at least one firstgate structure 15. In some examples, the dielectric cap layer 30 and thedielectric layer that is present on the at least one first gatestructure 15 can be removed before removing the mandrel structure 20. Inone embodiment, the etch process for removing the mandrel structure 20may be an anisotropic etch, such as reactive ion etch (RIE), or the etchprocess may be an isotropic etch, such as a wet chemical etch. In oneexample, a wet etch composed of H₃PO₄ may be used to remove a dielectriccap layer 30 composed of silicon nitride, and a wet etch composed ofNH₄/H₂O₂ may be used to remove a mandrel structure 20 composed ofgermanium. In one embodiment, the process of removing the mandrelstructure 20 and the dielectric cap layer 30 includes patterning aphotoresist layer to cover the region of the substrate 5 thatcorresponds to the p-type semiconductor devices, and removing thedielectric cap layer 30 with a wet etch of hydrofluoric (HF) acid thatis selective to oxide or a reactive ion etch process. Thereafter, thepatterned photoresist layer is removed from the region of the substratecorresponding to the p-type semiconductor devices and another patternedphotoresist layer is formed over the portion of the substratecorresponding to the n-type semiconductor devices, in which at least themandrel structure 20 is exposed. The exposed mandrel structure 20 isthen removed using a selective wet etch or plasma etch, such as XeF₂.

FIG. 6 depicts forming a second gate structure 45 on the III-V finstructures 40. In one embodiment, the second gate structure 45 includesat least one second gate dielectric layer 43 and at least one secondgate conductor layer 44. The at least one second gate dielectric layer43 is typically formed on the channel portion of the III-V fin structure40. The at least one second gate dielectric layer 43 of the second gatestructure 45 may be composed of any dielectric material includingoxides, nitrides and oxynitrides. In one embodiment, the at least onesecond gate dielectric layer 43 may be provided by a high-k dielectricmaterial. In one embodiment, the at least one second gate dielectriclayer 43 is composed of a high-k oxide such as, for example, HfO₂, ZrO₂,Al₂O₃, TiO₂, La₂O₃, SrTiO₃, LaAlO₃, Y₂O₃ and mixtures thereof. Otherexamples of high-k dielectric materials for the at least one second gatedielectric layer 43 include hafnium silicate, hafnium silicon oxynitrideor combinations thereof. In one embodiment, the at least one second gatedielectric layer 43 may be deposited by chemical vapor deposition (CVD).Variations of CVD processes suitable for depositing the at least onesecond gate dielectric layer 43 include, but are not limited to, APCVD,LPCVD, PECVD, MOCVD, ALD, and combinations thereof. In one embodiment,the thickness of the at least one second gate dielectric layer 43 isgreater than 0.8 nm. More typically, the at least one second gatedielectric layer 43 has a thickness ranging from about 1.0 nm to about6.0 nm.

The at least one second gate conductor layer 44 is formed on the atleast one second gate dielectric layer 43. The at least one second gateconductor layer 44 may be formed by a deposition process, such as CVD,plasma-assisted CVD, plating, and/or sputtering, followed byplanarization. In one embodiment, the at least one second gate conductorlayer 44 is composed of metal or a doped semiconductor. Examples ofmetals that may be employed for the at least one second gate conductorlayer 44 may include, but is not limited to, W, Ni, Ti, Mo, Ta, Cu, Pt,Ag, Au, Ru, Ir, Rh, and Re, Al, TiN, WN, TaN, TiAlN, TaAlN, and alloysthereof. One example of a doped semiconductor that is suitable for theat least one second gate conductor layer 44 is doped polysilicon.

In some embodiments, in which the first conductivity finFET that isformed in the second device region of the substrate 5 is an n-typefinFET, the at least one second gate conductor layer 44 may include ametal that is an n-type work function metal layer. As used herein, an“n-type work function metal layer” is a metal layer that effectuates ann-type threshold voltage shift. “N-type threshold voltage shift” as usedherein means a shift in the Fermi energy of an n-type semiconductordevice towards a conduction band of silicon in a silicon-containingsubstrate of the n-type semiconductor device. The “conduction band” isthe lowest lying electron energy band of the doped material that is notcompletely filled with electrons. In one embodiment, the work functionof the n-type work function metal layer ranges from 4.1 eV to 4.3 eV. Inone embodiment, the n-type work function metal layer is composed of atleast one of TiAl, TanN, TiN, HfN, HfSi, or combinations thereof. Then-type work function metal layer can be deposited using chemical vapordeposition (CVD), atomic layer deposition (ALD), sputtering or plating.In one embodiment, the n-type work function metal layer is composed oftitanium aluminum (TiAl) and is deposited using sputtering. Examples ofsputtering apparatus that may be suitable for depositing the n-type workfunction metal layer include DC diode type systems, radio frequency (RF)sputtering, magnetron sputtering, and ionized metal plasma (IMP)sputtering. In one example, an n-type work function metal layer composedof TiN is sputtered from a solid titanium target, in which the nitrogencontent of the metal nitride layer is introduced by a nitrogen gas. Inanother example, an n-type work function metal layer composed of TiN issputtered from a solid target comprised of titanium and nitrogen. Inaddition to physical vapor deposition (PVD) techniques, the n-type workfunction metal layer may also be formed using chemical vapor deposition(CVD) and atomic layer deposition (ALD). The at least one second gatestructure 44 may be formed using deposition, photolithography and etchprocesses.

Following the formation of the second gate structure 45, source regions50 a, 50 b and drain regions 55 a, 55 b may be formed on the germaniumcontaining fin structures 10 and the III-V fin structures 40. In someembodiments, the process sequence for forming the source regions 50 a,50 b and drain regions 55 a, 55 b includes forming a spacer 16 on asidewall of the gate structure 15, 45, and forming the source regions 50a, 50 b and drain regions 55 a, 55 b on opposing sides of the gatestructure 15, 45. In some examples, the exposed portions of thegermanium containing fin structures 20 and the exposed portions of theIII-V fin structures 40 may be doped to provide source and drainextension regions. The source and drain extension regions formed in thegermanium containing fin structures 10 may be p-type doped to provide ap-type conductivity fin field effect transistor. The source and drainextension regions to the III-V fin structures 40 may be n-type doped toprovide an n-type conductivity fin field effect transistor.

Following the formation of the source and drain extension regions,epitaxially formed source regions 50 a, 50 b and drain regions 55 a, 55b may be formed on the germanium containing fin structures 10 and theIII-V fin structures 40. The epitaxially formed source regions 50 a, 50b and drain regions 55 a, 55 b have a conductivity that is typicallysimilar to the conductivity of the source and drain extension regions.For example, the epitaxially formed source regions 50 a and drainregions 55 a that are formed on the germanium containing fin structure10 may be doped to a p-type conductivity to provide a p-type finFETdevice. The epitaxially formed source regions 50 b and drain regions 55b that are formed on the III-V fin structure 40 may be doped to ann-type conductivity to provide an n-type finFET device.

FIGS. 1-6B depict a gate first process. In another embodiment, theprocess sequence for forming finFET devices including the germaniumcontaining fin structures 10 and the III-V fin structures 40 includes agate last process sequence, which is not depicted in the suppliedfigures. A gate last process includes forming a replacement gatestructure on the channel portion of the fin structures, e.g., germaniumcontaining fin structures 10 and III-V fin structures 40, forming aspacer on the sidewall of the replacement gate structure, forming sourceand drain regions on opposing sides of the replacement gate structure,removing the replacement gate structure, and forming a functional gatestructure in the space once occupied by the replacement gate structure.The replacement gate structure can include sacrificial material thatdefines the geometry of a later formed functional gate structure thatfunctions to switch the semiconductor device from an “on” to “off”state, and vice versa. A process sequence employing a replacement gatestructure may be referred to as a “gate last” process sequence. Bothgate first and gate last process sequences are applicable to the presentdisclosure.

In another aspect, the present disclosure provides a semiconductordevice that includes a substrate 5 having a first device region and asecond device region. In one embodiment, a p-type fin field effecttransistor 100 a is present in the first device region. The p-type finfield effect transistor 100 a includes a first fin structure comprisedof a germanium containing material, i.e., germanium containing finstructure 10. In one embodiment, an n-type fin field effect transistoris simultaneously present in the second device region. The n-type finfield effect transistor includes a second fin structure comprised ofIII-V semiconductor material, i.e., III-V fin structure 40.

While the present disclosure has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present invention. It is therefore intended that the presentinvention not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

What is claimed is:
 1. A method of fabricating a semiconductor devicecomprising: proving a substrate having a germanium containing layer thatis present on a dielectric layer; etching the germanium containing layerof the substrate to provide a first region including a germaniumcontaining fin structure and a second region including a mandrelstructure; forming a first gate structure on the germanium containingfin structure; forming a III-V fin structure on a sidewall of themandrel structure; removing the mandrel structure; and forming a secondgate structure on the III-V fin structure.
 2. The method of claim 1,wherein the germanium containing fin structure has a width ranging from2 nm to 12 nm, and the mandrel structure has a width ranging from 15 nmto 45 nm.
 3. The method of claim 1, wherein the substrate includes asemiconductor on insulator substrate, wherein the SOI substrate includesa semiconductor on insulator (SOI) layer on the dielectric layer,wherein the SOI layer provides the germanium containing layer.
 4. Themethod of claim 1, wherein the germanium containing layer is silicongermanium or germanium.
 5. The method of claim 1, wherein the etching ofthe substrate comprises: forming a mask protecting portions of thegermanium containing layer that provide the germanium containing finstructure and the mandrel structure; etching exposed portion of thegermanium containing layer with an anisotropic etch; and removing themask.
 6. The method of claim 1, wherein forming the first gate structureon the germanium containing fin structure comprises: depositing a firstgate dielectric layer on the first region and second region of thesubstrate; depositing a first gate conductor layer on the first regionand second region of the substrate; forming first block mask over thefirst region, wherein the first block mask is not present over thesecond region; and removing a portion of the first gate dielectric layerand the first gate conductor layer in the second region.
 7. The methodof claim 1, wherein forming the III-V fin structure on the sidewall ofthe mandrel structure comprises an epitaxial growth process.
 8. Themethod of claim 1, wherein the III-V fin structure has a width rangingfrom 2 nm to 12 nm.
 9. The method of claim 1, wherein removing themandrel structure comprises an etch process that is selective to theIII-V fin structures.
 10. The method of claim 1, wherein forming thesecond gate structure on the III-V fin structure comprises: depositing asecond gate dielectric layer on the first region and second region ofthe substrate; depositing a second gate conductor layer on the firstregion and second region of the substrate; forming a second block maskover the second region, wherein the block mask is not present over thefirst region; and removing the portion of the second gate dielectriclayer and the second gate conductor layer in the first region.
 11. Themethod of claim 1 further comprising forming a source region and a drainregion on the III-V fin structure and the germanium containing finstructure.